/* infcodes.c -- process literals and length/distance pairs
 * Copyright (C) 1995-1998 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

#include "zutil.h"
#include "inftrees.h"
#include "infblock.h"
#include "infcodes.h"
#include "infutil.h"
#include "inffast.h"

/* simplify the use of the inflate_huft type with some defines */
#define exop word.what.Exop
#define bits word.what.Bits

   typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
      START,    /* x: set up for LEN */
      LEN,      /* i: get length/literal/eob next */
      LENEXT,   /* i: getting length extra (have base) */
      DIST,     /* i: get distance next */
      DISTEXT,  /* i: getting distance extra */
      COPY,     /* o: copying bytes in window, waiting for space */
      LIT,      /* o: got literal, waiting for output space */
      WASH,     /* o: got eob, possibly still output waiting */
      END,      /* x: got eob and all data flushed */
      BADCODE}  /* x: got error */
   inflate_codes_mode;

/* inflate codes private state */
   struct inflate_codes_state {
   
   /* mode */
      inflate_codes_mode mode;      /* current inflate_codes mode */
   
   /* mode dependent information */
      uInt len;
      union {
         struct {
            inflate_huft *tree;       /* pointer into tree */
            uInt need;                /* bits needed */
         } code;             /* if LEN or DIST, where in tree */
         uInt lit;           /* if LIT, literal */
         struct {
            uInt get;                 /* bits to get for extra */
            uInt dist;                /* distance back to copy from */
         } copy;             /* if EXT or COPY, where and how much */
      } sub;                /* submode */
   
   /* mode independent information */
      Byte lbits;           /* ltree bits decoded per branch */
      Byte dbits;           /* dtree bits decoder per branch */
      inflate_huft *ltree;          /* literal/length/eob tree */
      inflate_huft *dtree;          /* distance tree */
   
   };


    inflate_codes_statef *inflate_codes_new(uInt bl, uInt bd, inflate_huft *tl, inflate_huft *td, z_streamp z){
      inflate_codes_statef *c;
   
      if ((c = (inflate_codes_statef *)
       ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
      {
         c->mode = START;
         c->lbits = (Byte)bl;
         c->dbits = (Byte)bd;
         c->ltree = tl;
         c->dtree = td;
      Tracev((stderr, "inflate:       codes new\n"));
      }
      return c;
   }


    int inflate_codes(inflate_blocks_statef *s, z_streamp z, int r){
      uInt j;               /* temporary storage */
      inflate_huft *t;      /* temporary pointer */
      uInt e;               /* extra bits or operation */
      uLong b;              /* bit buffer */
      uInt k;               /* bits in bit buffer */
      Bytef *p;             /* input data pointer */
      uInt n;               /* bytes available there */
      Bytef *q;             /* output window write pointer */
      uInt m;               /* bytes to end of window or read pointer */
      Bytef *f;             /* pointer to copy strings from */
      inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
   
   /* copy input/output information to locals (UPDATE macro restores) */
      LOAD
   
   /* process input and output based on current state */
      while (1) 
         switch (c->mode)
         {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
            case START:         /* x: set up for LEN */
            #ifndef SLOW
               if (m >= 258 && n >= 10)
               {
                  UPDATE
                  r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
                  LOAD
                  if (r != Z_OK)
                  {
                     c->mode = r == Z_STREAM_END ? WASH : BADCODE;
                     break;
                  }
               }
            #endif /* !SLOW */
               c->sub.code.need = c->lbits;
               c->sub.code.tree = c->ltree;
               c->mode = LEN;
            case LEN:           /* i: get length/literal/eob next */
               j = c->sub.code.need;
               NEEDBITS(j)
               t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
               DUMPBITS(t->bits)
               e = (uInt)(t->exop);
               if (e == 0)               /* literal */
               {
                  c->sub.lit = t->base;
               Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
                 "inflate:         literal '%c'\n" :
                 "inflate:         literal 0x%02x\n", t->base));
                  c->mode = LIT;
                  break;
               }
               if (e & 16)               /* length */
               {
                  c->sub.copy.get = e & 15;
                  c->len = t->base;
                  c->mode = LENEXT;
                  break;
               }
               if ((e & 64) == 0)        /* next table */
               {
                  c->sub.code.need = e;
                  c->sub.code.tree = t + t->base;
                  break;
               }
               if (e & 32)               /* end of block */
               {
               Tracevv((stderr, "inflate:         end of block\n"));
                  c->mode = WASH;
                  break;
               }
               c->mode = BADCODE;        /* invalid code */
               z->msg = (char*)"invalid literal/length code";
               r = Z_DATA_ERROR;
               LEAVE
            case LENEXT:        /* i: getting length extra (have base) */
               j = c->sub.copy.get;
               NEEDBITS(j)
               c->len += (uInt)b & inflate_mask[j];
               DUMPBITS(j)
               c->sub.code.need = c->dbits;
               c->sub.code.tree = c->dtree;
            Tracevv((stderr, "inflate:         length %u\n", c->len));
               c->mode = DIST;
            case DIST:          /* i: get distance next */
               j = c->sub.code.need;
               NEEDBITS(j)
               t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
               DUMPBITS(t->bits)
               e = (uInt)(t->exop);
               if (e & 16)               /* distance */
               {
                  c->sub.copy.get = e & 15;
                  c->sub.copy.dist = t->base;
                  c->mode = DISTEXT;
                  break;
               }
               if ((e & 64) == 0)        /* next table */
               {
                  c->sub.code.need = e;
                  c->sub.code.tree = t + t->base;
                  break;
               }
               c->mode = BADCODE;        /* invalid code */
               z->msg = (char*)"invalid distance code";
               r = Z_DATA_ERROR;
               LEAVE
            case DISTEXT:       /* i: getting distance extra */
               j = c->sub.copy.get;
               NEEDBITS(j)
               c->sub.copy.dist += (uInt)b & inflate_mask[j];
               DUMPBITS(j)
            Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
               c->mode = COPY;
            case COPY:          /* o: copying bytes in window, waiting for space */
            #ifndef __TURBOC__ /* Turbo C bug for following expression */
               f = (uInt)(q - s->window) < c->sub.copy.dist ?
                  s->end - (c->sub.copy.dist - (q - s->window)) :
                  q - c->sub.copy.dist;
            #else
            f = q - c->sub.copy.dist;
            if ((uInt)(q - s->window) < c->sub.copy.dist)
            f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));
            #endif
               while (c->len)
               {
                  NEEDOUT
                  OUTBYTE(*f++)
                  if (f == s->end)
                     f = s->window;
                  c->len--;
               }
               c->mode = START;
               break;
            case LIT:           /* o: got literal, waiting for output space */
               NEEDOUT
               OUTBYTE(c->sub.lit)
               c->mode = START;
               break;
            case WASH:          /* o: got eob, possibly more output */
               if (k > 7)        /* return unused byte, if any */
               {
               Assert(k < 16, "inflate_codes grabbed too many bytes")
                  k -= 8;
                  n++;
                  p--;            /* can always return one */
               }
               FLUSH
               if (s->read != s->write)
               LEAVE
               c->mode = END;
            case END:
               r = Z_STREAM_END;
               LEAVE
            case BADCODE:       /* x: got error */
               r = Z_DATA_ERROR;
               LEAVE
            default:
               r = Z_STREAM_ERROR;
               LEAVE
         }
   #ifdef NEED_DUMMY_RETURN
   return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
   #endif
   }


    void inflate_codes_free(inflate_codes_statef *c, z_streamp z){
      ZFREE(z, c);
   Tracev((stderr, "inflate:       codes free\n"));
   }
